X-flow Tall Block Water Pump Bolts

[JonnyPlus2]

Hi All;
I'm starting my 1760 Twink engine build and my first step is to bolt a plate with a water hose adapter over the water pump inlet to test that the block's not porous. The Lotus manual says that the two lower bolts are 1/4 unC (which they are) and the other one is 1/4 unF. I'm not confident that the X-flow block has a 1/4 unF thread at the top mounting hole. I'm going to get a tap this evening to see if I can clean it out but I would like to know if it is supposed to be 1/4 unF. (28 thread).
Can someone confirm or deny this, please and thanks. Much appreciated.

[promotor]

Hi All;
I'm starting my 1760 Twink engine build and my first step is to bolt a plate with a water hose adapter over the water pump inlet to test that the block's not porous. The Lotus manual says that the two lower bolts are 1/4 unC (which they are) and the other one is 1/4 unF. I'm not confident that the X-flow block has a 1/4 unF thread at the top mounting hole. I'm going to get a tap this evening to see if I can clean it out but I would like to know if it is supposed to be 1/4 unF. (28 thread).
Can someone confirm or deny this, please and thanks. Much appreciated.

Can you post a photo of the bolt hole(s) in question just to clarify please?

[ncm]

If you are looking to cover the waterpump hole machined into the block, then the top and lower left bolt holes are 1/4 unc, the lower right is 5/16 unc. Presumably Ford used the larger bolt to accommodate the loads applied by the dynamo/alternator adjusting strap which is held by this bolt in the pushrod engine application.

Brian.

[mbell]

I'm going to get a tap this evening to see if I can clean it out

Personally I bought some thread cleaning tools rather than use taps, to avoid risking damage to the thread caused by the tap.

[seniorchristo]

Johnny B
How are you getting your 1760cc? Are you using a 77.62mm stroke crankshaft and oversize +.060" bore? If so, are you measuring wall thickness with ultrasound testing? I'd like to build such a 1760 motor but am wary of the wall thickness.
Thanks
Chris

[JonnyPlus2]

Hi Brian,
Thanks much for the great info, My mistake was due to the local hardware store having a 5/16 bolt in the 1/4 bolt bin so I bought a 1/4" and a 5/16" bolt thinking I had bought two 1/4" bolts!

Promotor:
Can't seem to get pics off my camera but the bolts in question are on page e.27 of the 1974 edition of the shop manual, Fig. 19 Timing Chest Bolts. The bolts are #2 and #3.

Chris: I got the block ultrasounded before I had it bored out. That was so long ago that I do not remember how much meat was there but I was pretty confident it was enough. Not confident enough to pass on the porosity test though!

This is a relatively well known and tested build and the general opinion is that it is relatively safe with an x-flow block as they apparently tend to have a little more meat in the bores.

Cheers,
Jonny G

[rgh0]

Its a myth about any particular block type such as the 1600 711 blocks have more meat around the bores, except perhaps the AX blocks but I have never got a chance to test any of those. All blocks vary due to casting tolerances and also where they are measured as the outside of the bore casting is not circular with the thinnest parts being at 0/90/180 and 270 degrees with 0 being the front of the engine and the thickest parts being in between.

cheers
Rohan

[JonnyPlus2]

Hey Rohan,
I know bugger all about this, I'm just repeating stuff from out there in the ether. The following is from Tuning Twin Cam Fords by David Vizard ". . . it would seem that the 1600 block has a little more metal around the bores in the first place . . ."
My block is allegedly an industrial unit that originally powered a street sweeper!

Cheers,

[rgh0]

Yes "it would seem...". Lots of similar references on the internet and in old articles but precious little actual measured data

The gap between the front and rear of adjacent cylinders is about as small as the casting technology which was the same during the life of the Kent blocks allowed. Potentially more metal could have been added on the thrust face of the bore but all the ultrasonic testing i have done on all the block types L block and non L block shows a similar average thickness and similar variation.

Based on my measurements of around 50 blocks of all types except the South African AX blocks. About 80% of all blocks will go safely to 83.5 mm with offset boring to centre the bore in the external bore casting where needed (which most do). Maybe 20% to 30% will go safely to 84mm maybe 3% to 5% will go to 85mm . By "Safely" I mean a minimum wall thickness of 2.5 mm. For a competition engine I like a minimum of 3mm especially in the thrust face area.

Cheers
Rohan

[reds4se]

As Brian posted above the bolts around the water-pump in the block are 1/4 and 5/16 UNC and are numbers 3 and 4 in the manual drawing you referred to. The UNF bolts are used at the edges of the front cover to hold the two parts together.
RB.

[JonnyPlus2]

Hi Rohan,

Well, I hope I'm not in for an unpleasant surprise! No wonder Dave Bean sold me those pistons for peanuts!
The cam I'm getting peaks out at about 7K, and I'll have the bottom end done up to take 7500 on occasion. Hopefully the block can take that (if it's not porous ).

Perhaps I will be forced, forced to buy a 2 litre alloy block.

You might want to consider creating a separate thread on your research and put it somewhere where it's easy to find. I wish I had know this before I handed over my spondulics to the late Mr. Bean.

Cheers.

[rgh0]

Get your block ultrasonically tested and if you're lucky you will be able to get 84mm out of it. Measure each bore at 90 degree intervals and post the results and I can advise on whether it will go to 84mm and how to offset the bores to achieve that if possible.

Pay attention to the thickness along the length of the bore as old blocks tend to have a lot of external corrosion from the water jacket side near the bottom of the water jacket where sludge has built up reducing the thickness in that area which can result in cracking around the centre main bearing and coolant leaking into the sump.

cheers
Rohan